Article excerpt

Fungus with a future

THE mushroom has always been a thing of mystery. In ancient times the seemingly miraculous manner of its growth without seed, its sudden appearance after rain, its equally rapid disappearance and its curious umbrella-like shape gave rise to a wealth of allusions and mythologies. Today, it is continuing to perform feats of magic and versatility, not only as a source of food, but by helping to convert agricultural and industrial wastes into useful matter.

Edible mushrooms provide high quality protein that can be produced with greater biological efficiency than animal protein. They are rich in fibre, minerals and vitamins, and have a low crude fat content. These properties are major contributing factors to the traditional recognition of mushrooms as "healthy" food.

However, although a large number of mushroom species are not only edible but also possess tonic and medicinal qualities, some are lethally poisonous. There is no simple way of distinguishing between edible and poisonous mushrooms, and one should eat mushrooms only if one knows their names and their properties with considerable precision.

Mushroom cultivation, moreover, requires relatively little in terms of large-scale equipment, capital, land and processing. In the rural areas of less-developed countries, where large-scale capital-intensive operations are inappropriate, well-managed mushroom farms can make important contributions to the nutrition and economic welfare of the local people. This is especially true in regions where the indigenous population suffers from protein deficiency.

Nature's garbage man

However, the mushroom would not be worthy of its versatile reputation if it were only a source of food. It can also help to solve one of humankind's most urgent and growing problems--its propensity to create waste.

The agricultural, forestry and food processing industries generate huge quantities of wastes, much of which is either burnt, discharged into watercourses or used for landfill. And yet it constitutes a potentially valuable resource. Most agricultural, industrial and household solid wastes are rich in organic matter, mainly cellulose, hemicellulose and lignin, substances that are highly resistant to biological degradation and have little or no food value in their original form. Furthermore, their disposal can be a major source of environmental pollution. However, when properly treated with bioconversion technology--the process whereby micro-organisms are used to transform organic residues into utility products--they can be modified and upgraded into high-quality protein for human and animal consumption, and used for the production of microbial metabolites and the generation of new feedstocks for the polymer industry, which creates materials such as plastics, resins and synthetic rubbers.

Edible mushroom production is a particularly effective form of bioconversion technology. Mushrooms differ from green plants in that they cannot use sunlight to manufacture their food. What they do is produce enzymes that degrade the complex substrates on which they grow and then feed themselves on the soluble substances thus produced. …